The present invention concerns simple methods of insecticide dispersal to exterminate termites and similar harmful insects living in or traversing the area under a house or building.
Application of insecticide under buildings and houses to exterminate termites is currently performed, and has been performed in the past. Former methods require workers to wear totally protective clothing, gloves, and gas masks, crawl under the building, and disperse chlordane or other insecticides over the entire exposed ground and/or coat wooden beams such as the groundsills with insecticide.
These former methods of applying insecticide are not only extremely laborious, but also require exterminators to work for long periods in the confined area under a building while breathing poisonous insecticide fumes. Hence, the work environment is extremely bad. Furthermore, These methods have the drawback that complete insecticide coverage of very cramped areas under some buildings is impossible because not all small, confined regions can be reached to apply insecticide.
In particular, it is extremely difficult for a worker, inside the area under a building, to apply insecticide with a brush or similar applicator in narrow gaps such as those between the floor boards. It is possible to apply liquid insecticide to the gaps and crevices even in confined areas by spraying. However, with this method atomized droplets of the sprayed insecticide float in the air under the building, and unfortunately, gas masks can not completely eliminate the poisonous particles. Hence, working conditions are made worse by making the worker breathe insecticide droplets. For the worker's protection, liquid insecticide application is restricted to organophosphate type insecticides with dispenser pressures of 5 Kg/square cm and below. It is impossible for exterminators to work for long periods in this type of hazardous environment, and it is therefore impossible to entirely cover the area under a building with insecticide by these methods.
In cases where total coverage is impossible, termites will establish a route into the home or building through the area where insecticide has not been applied. For example, even though almost all of the area under a building may be covered with insecticide, one uncovered area will drastically reduce the effect of the overall extermination.
By former methods where workers enter the enclosed area under a building and disperse and/or apply insecticide with a brush, not only is it impossible to entirely cover all the exposed surfaces, but it is clearly impossible to apply insecticide in all the narrow crevices, as well as open areas exposed only through narrow crevices.
For these reasons, recently adopted methods of insecticide application basically involve coating the entire surface of the ground under the building with organic salt type insecticides such as chlordane, which do not degrade easily, and hence remain effective for extremely long periods. These methods take advantage of the ease of application to the ground surface, and prevent insect penetration at that point.
Today, these techniques are being re-evaluated based on conjecture that they may bring about serious environmental pollution problems in the future. However, regardless of future environmental problems, no improved harmful insect extermination methods have been developed to replace these techniques, and they are still used for termite extermination.
As mentioned, insecticides like chlordane have the special attribute that they remain on or in the ground without degrading, and hence provide long term effectiveness against harmful insects. On the other hand, it is impossible to keep the insecticide within the area under the building forever, and the substance inevitably seeps into the ground water along with rain water to pollute plants and vegetables, domestic animals which feed on the plants, and humans that eat the plants and animals. According to recent reports, chlordane has been detected even in animals of the South Pole, which is assumed to be the most unpolluted area on earth.
It has recently been proposed that organophosphates be used instead of organic salt type insecticides. Organic salt type insecticides gradually accumulate in the human body over a long period, and when the accumulated quantity exeeds a critical value, severe impairment results without warning. By the time symptoms are recognized, it is too late for treatment, and recovery is impossible. Conversely, even a small quantity of organophosphate type insecticide attached to the skin or breathed into the body has a strong poisonous reaction which can be immediately treated. However, even though treatment can normally be performed in time, since organophosphates are extremely poisonous to humans, workers must take preventive measures that would not even be considered using chlordane. During the application of organophosphates, people in the vicinity of the house or building as well as those in the building must be evacuated, and particular care must be taken to insure that atomized insecticide does not leak out of the enclosed area under the building.
An ideal harmful insect extermination method could be realized with an insecticide which degrades rapidly in the ground yet has sufficient strength to exterminate insects. Unfortunately, since such insecticides are applied to the ground, they loose effectiveness rapidly, and long term effective harmful insect extermination is impossible.
The inventor proposed that workers remain outside the area under the building, and that harmful insect penetration into the building be stopped at the foundation, the groundsills, the support beams, the floor beams, and the floor boards, rather than at the ground. With this in mind he has experimented with various application methods.
The first experiment attempted to obtain complete coverage by spraying liquid insecticide, atomized by compressed air pressure, from a nozzle inserted into the area under the building. Although insecticide coverage by this method was obtained in the vicinity of the nozzle, complete coverage of all the exposed surfaces in the enclosed area under the building could not be accomplished. The inventor performed many experiments varying the nozzle shape, the nozzle opening size, the compressed air pressure, etc., but was unable to realize complete insecticide coverage. However, these experiments made one effect clear. Namely, as the nozzle opening is made smaller and the compressed air pressure is increased, the atomized particles become smaller and remain airborne longer, and conversely as the nozzle opening is made larger and the air pressure is decreased, the ejected particles become larger and are less buoyant in the air. Although the small buoyant particles remain airborne for some time, complete insecticide coverage under the building is not obtained, and the large particles primarily fall to the ground in front of the nozzle.
From these results, the inventor reasoned that since the fine particles ejected from the nozzle possess considerable kinetic energy, this energy could be used to stir up the air underneath the building, and since the particles remain airborne for a fixed period, the particles would mix with, and be carried to all parts of the enclosed area under the building by the turbulent air. In this way, it would be possible to obtain complete insecticide coverage without entering the enclosed area under the building. However, attaining insecticide particle buoyancy and inducing turbulence in the air are reciprocal operations, and both could not be satisfactorily achieved simultaneously. This inverse relationship results for the following reason. Since the kinetic energy of atomized particles ejected from the nozzle is proportional to the particle mass and particle velocity squared, either the nozzle exit speed or the mass ejected from the nozzle must be increased to increase turbulence in the air. However, in order to increase the nozzle exit speed, the compressed air pressure is increased, and the particle size, and hence the particle mass is reduced. If the nozzle opening is increased to increase the particle mass, particle buoyancy suffers, and the particles fall earthward immediately after ejection. Consequently, simultaneous fulfillment of these reciprocal requirements, or even a satisfactory trade-off was impossible using an atomized liquid insecticide. Further, it was impossible to spray liquid insecticides into the air from a small nozzle and obtain a narrow jet of atomized insecticide. Hence it was impossible to transfer the fluid energy of a narrow high speed insecticide jet to accelerate the air enclosed in the area under the building in a given direction. As a result, liquid insecticides could not be dispersed to all points under the building by simultaneously stirring up the enclosed air, and mixing a buoyant insecticide mist in that turbulent air. Furthermore, liquid insecticides have the drawback that their adherence to objects is too strong. This property makes most of the liquid insecticide adhere to objects immediately in front of the nozzle prior to ever being transported to the rest of the area under the building.
In further experiments, the inventor was able increase the specific gravity of the ejected insecticide particles independent of the compressed air pressure by using a solid insecticide in powdered form, and was thus able to eject fixed sized particles at a high speed in a specific direction by using a high compressed air pressure. Also, by making the insecticide adhesion less than that of liquid insecticides, the inventor was successful in coating all surfaces, crevices, and areas accessible only through narrow crevices, from outside the enclosed area under the building, to a degree unimaginable by former methods.
Consequently, the first major objective of this invention is to provide a highly effective method of exterminating insects under the floor of a house or building, by which all exposed surfaces can be completely covered with insecticide applied by a simple procedure by workers outside the area under the building.
The inventor has previously developed a harmful insect exterminating trough (Japanese Patent Application No. 115241/1984), which is attached all along the foundation, is filled with insecticide, and prevents the intrusion of insects by killing those that contact the insecticide. To the extent that this trough can be attached to the foundation without any gaps, and can be filled with insecticide in a continuous line, excellent harmful insect deterent properties can be achieved.
However, this trough system has the disadvantage that it is a time consuming job to attach a trough or groove all along the foundation, and in cases where the concrete foundation surface is not planar, and/or the foundation takes on a complicated shape, it is very difficult to attach the trough without creating gaps between the trough and the foundation. In the event that a gap wide enough for insects to pass is formed between the foundation and the trough or groove, harmful insects will penetrate into the home or building through this gap, and the effectiveness of the insect barrier is thus, greatly reduced. Also, if there is a break in the continuous line of insecticide filling the trough, harmful insects will similarly penetrate into the home or building through this pathway. Therefore, this system has the disadvantage that extreme care must be taken to avoid gaps when attaching the trough to the foundation, and when loading insecticide into the trough, and hence, installation and insecticide application are time consuming and difficult.
Harmful insect barrier systems using liquid, rather than powdered insecticides have previously been developed (Japanese Patent Public Notice No. 3529/1979, Japanese Utility Model Public Notice No. 33289/1979). In these insect barrier systems, liquid insecticide is poured into a trough at one inlet point, and flows from that point to all parts of the trough. To insure that insecticide flows uniformly to all parts of the trough, the trough must be accurately fixed to the foundation such that it is level at all points. These systems thus have the disadvantage that installation of troughs, which are level throughout, is extremely labor intensive. They also have the disadvantage that foundation settling over time upsets the trough's levelness, and as a result insecticide may not flow to all parts of the trough.
As mentioned previously, in order to avoid pollution of the ground water, it is necessary to use insecticides which are not as long lasting as chlordane. When these short term insecticides are used, it becomes necessary to reapply insecticide every 5 or 10 years. Trough type insect barrier systems have the disadvantage that insecticide reapplication and long term maintenance are troublesome operations.
The second major objective of this invention is, therefore, to provide a method of exterminating insects under the floor of a house or building by establishing an unbroken barrier of insecticide all along the foundation. This objective would eliminate the disadvantages of present barrier systems by piling insecticide, without creating gaps, on the foundation, regardless of whether a trough is attached or not, and regardless of whether there are outcroppings and voids in the foundation or the foundation takes on a complicated shape.
Another major objective of this invention is to attach insecticide to, and completely cover the foundation, groundsills, support beams, floor beams, and floor boards, thus allowing extermination using insecticides which degrade in the ground over a short period, and drastically reducing environmental pollution.
Another major objective of this invention is to apply insecticide without requiring workers to enter the enclosed area under the building, thus allowing application even under low to the ground floors where workers cannot enter, as well as greatly improving working conditions by avoiding insecticide ingestion.
A further major objective of this invention is to use compressed air pressure to accelerate insecticide into the enclosed area under a building without introducing large quantities of air, and hence, to minimize the leakage of insecticide outside of that area during application.
A final major objective of this invention is to provide a method of exterminating insects under the floor of a house or building, which can maintain complete long term protection against harmful insects by simple insecticide reapplication.
The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for purpose of illustration only and is not intended as a definition of the limits of the invention.